Method and device for application of thin objects

ABSTRACT

The present invention relates to a method of and an apparatus for separation and application of thin objects of a non-porous material or of a material of low porosity on a surface. The invention also relates to a package for the thin objects. With the aid of a pick up and lay down head on an application means a vacuum is applied on a part, preferably the middle, of the uppermost object in a stack of thin objects being in a recess of a package. The recess of the package for receiving the objects is at least areawise somewhat smaller than the exterior dimensions of the objects. With the aid of vacuum in the pick up and lay down head the uppermost object is lifted out of the package. The underlying objects in the stack remain in the package by the friction and scrape effects towards the interior walls of the package. Then the pick up and lay down head of the application means is lowered down so that the object is brought into contact with the surface.

This application is a Divisional of application Ser. No. 10/146,950,filed on May 17, 2002 now U.S. Pat. No. 6,843,474, and for whichpriority is claimed under 35 U.S.C. § 120; and this application claimspriority of Application No. 0101740-9 filed in Sweden on May 17, 2001under 35 U.S.C. § 119; the entire contents of all are herebyincorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a method of separation and applicationof thin objects of a non-porous material or of a material of lowporosity on a surface for biological and/or chemical reactions. Theinvention further relates to an apparatus for automatic separation andapplication of these objects and a package for the thin objects.

To determine various substances' ability of inhibiting or promotinggrowth of e.g. a microorganism, the substances are applied on acultivation surface for the organism. This is accomplished by applying acarrier on the cultivation surface, on which carrier one or moresubstances are present in a predetermined and defined concentrationpattern. Then the substances diffuse into the cultivation surface, e.g.agar, and the desired concentration pattern of substance(s) is achievedin the cultivation medium. After incubation of the cultivation mediumwith the substance and the microorganism to be tested, the result isnormally read by measuring the inhibition zone. Various examples of howto perform this is illustrated i.a. in EP 0 157 071 and EP 0 444 390.These patents describe how to transfer a predetermined and definedconcentration pattern of substances with the aid of thin, rectangular orsquare carriers having the substance(s) in the predeterminedconcentration pattern. These carriers, also called test strips, are verythin and made of a non-porous material or a material of low porosity,e.g. some kind of plastic material. They are applied manually on thecultivation surface as it has been difficult to achieve a more automatedseparation and application. So far these strips have been packed instacks in blister packs of some suitable plastic material with smoothinterior walls and of a dimension somewhat larger than that of the teststrips. When picking up the uppermost strip from such a package it isdifficult to pick up only that one without picking up a number ofunderlying strips due to adherence e.g. by static electricity.

U.S. Pat. No. 5,026,039 describes a method of feeding sheets from astack of sheets in e.g. a copying machine using vacuum to lift theuppermost sheet. During the feeding a leaf spring is adapted in thepaper path to separate the uppermost sheet from the subsequent sheet sothat only one sheet is fed at the time.

SUMMARY OF THE INVENTION

Not applicable.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The invention is closer described in the following non-limitingembodiments illustrated on the enclosed drawings. In the embodimentshown the thin objects are rectangular, and

FIG. 1 shows an embodiment of an apparatus of the invention,

FIG. 2 shows an embodiment of the package of the invention,

FIG. 3 shows in enlargement a part of the package and

FIG. 4 shows one step of the process of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a method of separation and applicationof thin objects of non-porous material or a material of low porosity ona surface for biological and/or chemical reactions. One example on sucha surface to be mentioned is that of a cultivation medium, e.g. asurface of agar or agarose. On the side of the thin objects that shallbe applied towards the surface there may be a predetermined and definedconcentration pattern of chemically or biologically active substances.The shape of the thin objects is non-limiting and they may be e.g.rectangular, square, oval or circular. By a pick up and lay down head onan application means vacuum is applied on a part, preferably the middle,of the uppermost object in a stack of the thin objects in a package. Arecess of the package for receiving the objects is at least areawisesomewhat smaller than the exterior dimensions of the objects. With theaid of the vacuum in the pick up and lay down head the uppermost objectis lifted out of the package. By the friction and scrape effects againstthe interior walls of the package the uppermost of the thin objects willduring the lifting movement attain a convex shape. However, theunderlying objects of the stack will be retained in the package with theaid of a friction and scrape effect against its interior walls.Thereafter the object is applied on the surface by lowering the pick upand lay down head of the application means so that the contact betweenthe object and the surface is maximized.

The expression biological and/or chemical reactions comprises thosementioned in EP 0 157 071 and EP 0 444 390.

In one embodiment the packages are applied on a rotateable disc. Thedesired package is put into position under the pick up and lay down headby rotating the disc, whereafter the uppermost object is lifted out ofthe package. Thereafter the rotateable disc is turned back into itsoriginal position and the object is applied on the surface by loweringthe pick up and lay down head. Then another package is brought intoposition under the pick up and lay down head and the next object islifted up with the aid of the pick up and lay down head. Then therotateable disc is turned back into its original position and the objectis applied on the surface. It is continued in this way until the desirednumber of objects has been applied on predetermined spots on thesurface.

In another embodiment the rotateable disc has openings between thepackages to allow the lowering of the pick up and lay down head to thesurface. In this embodiment the desired package is brought in a positionunder the pick up and lay down head, the uppermost object is lifted outof the package and the rotateable disc is turned so that the pick up andlay down head is brought into position above the closest opening in thedisc. Thereafter the object is applied on the surface by lowering thepick up and lay down head through the opening.

In still another embodiment it is the application means that is turnedso that the pick up and lay down head is brought into position above thepackage from which an object is to be picked up. By the pick up and laydown head the object is removed from the package, whereafter theapplication means is turned into a position above the surface on whichthe object is to be applied. Thereafter the object is applied on thesurface by lowering the pick up and lay down head. Then the applicationmeans is turned so that it comes into position above the next desiredpackage. The uppermost object in this package is picked up, theapplication means is turned back into position above the surface and theobject is applied thereon. It is continued in this way until the desirednumber of objects have been applied on predetermined spots on thesurface.

In one embodiment of the invention the thin objects are applied in apredetermined order and on predetermined spots of the surface.

Non-limiting examples on non-porous material or material of low porosityare plastics, such as polyacrylamide, polyester, polyamide,polycarbonate or similar material.

The present invention also concerns an apparatus for separation andapplication of thin objects of a non-porous material or a material oflow porosity on a surface for biological and/or chemical reactions. Theshape of the thin objects is non-limiting, and they can e.g. berectangular, square, oval or circular. The apparatus comprises one ormore holders for packages for the thin objects, which holders areapplied on a rotateable disc, and an application means having a pick upand lay down head that can be lifted and lowered. This head is designedto be lowered into the recess of a package, and it is flexibly suspendedin the application means. The disc can be rotated from its originalposition so that each of the packages can be brought into a positionbelow the pick up and lay down head. On the pick up and lay down head avacuum may be applied or released to pick up the uppermost object in thepackage and apply it on the surface, respectively. The apparatus furthercomprises a holder for the surface on which the object is to be applied.The holder is rotateable and when an object is applied on the surfaceand the pick up and lay down head has been raised to fetch a new objectfrom the package, the holder is rotated and thereby the surface so thatthe next object is applied on another spot on the surface.

A driving device is connected to the rotateable disc to move it in apredetermined moving scheme. Another driving device is connected to therotateable holder for the surface on which the objects are to beapplied. In this way the apparatus can be set so that it lifts the thinobjects one by one from the packages in a predetermined order andapplies them on predetemined positions on the surface.

One embodiment of the present invention concerns an apparatus comprisingone or several holders for packages of the thin objects, which holdersare applied on a disc, an application means being rotateable around anaxis and having a pick up and lay down head that may be lifted up andlowered down. This head is so designed that it can be lowered into therecess and is flexibly suspended in the application means. On the pickup and lay down head a vacuum can be applied or released for lifting upthe uppermost object in the package, its separation from the otherobjects of the package and its application on the surface, respectively.The apparatus further comprises a rotateable holder for the surface onwhich the objects are to be applied.

A driving device is connected to the application means to move thisalong a predetermined moving scheme. Another driving device is connectedto the rotateable holder for the surface on which the objects are to beapplied. In this way the complete apparatus can be set so that it liftsthe thin objects one by one from the packages in a predetermined orderand applies them on predetermined positions on the surface.

The shape of the pick up and lay down head is not limiting and it may bee.g. rectangular, square, oval or circular. A channel extends in themiddle of the pick up and lay down head through which a vacuum may beapplied.

Further the invention concerns a package for thin objects of non-porousmaterial or material of low porosity. The shape of the thin objects isnon-limiting, and they may be e.g. rectangular, square, oval orcircular. The package is of a soft, bendable material with a recess forreceiving the objects, which recess at least areawise, is somewhatsmaller than the exterior dimensions of the objects.

In one shown embodiment of the invention the recess for receiving ofobjects in the package is in its width somewhat smaller than the widthof the objects.

The package may be of any shape, the essential thing is that the recessat least areawise is somewhat smaller than the exterior dimensions ofthe objects. Examples of suitable material for the packages are foamedplastic, cellular plastic, expanded rubber and foamed rubber with openor closed cells with or without a crosslinked molecular structure.Examples of such materials are low or high density polyethene,polypropene, vinyl plastic, polystyrene, polyurethane and the like. Whenremoving an object from the package the rough wall rims of the cells inthe recess of the package create an irregular friction against theobjects. A consequence of this is that the uppermost object is liftedout of the package while the underlying objects of the stack remain inthe package.

In one preferred embodiment the packages may have a bottom of a somewhatstiffer material, which facilitates the handling. The material in thebottom may be the same as in the other parts of the package, but inembodiments with a stiffer material in the bottom this material has ahigher density than that of the other part of the package.

FIG. 1 shows an apparatus 10 with application means 12 for separationand application of thin objects of non-porous material or material oflow porosity on a surface for biological and/or chemical reactions, suchas the surface of a cultivation medium. The apparatus 10 comprises aholder 17 for packages 24 of the thin objects. The packages areexchangeable. These holders 17 are applied on a rotateable disc 16. Inthe disc 16 there are openings 13 between the surfaces that are occupiedby the packages 24. The disc rotates around an axis 25. A pick up andlay down head 14 that can be lifted up and lowered down is flexiblysuspended in the application means 12. In the middle of the pick up andlay down head is a channel 15, through which a vacuum can be applied.The disc 16 is connected to a driving device (not shown) and theapparatus 10 can with the aid of the panel 18 be set so that it liftsthe objects out of the packages 24 in a predetermined order. Further theapparatus 10 comprises a rotateable holder 19 for the surface on whichthe thin objects 22 are applied. In the embodiment shown it is an agarsurface in a Petri dish 20. The holder 19 is connected to a drivingdevice (not shown).

FIG. 2 shows an embodiment of a package 24 for thin objects 22 ofnon-porous material or a material of low porosity having a predeterminedand defined concentration pattern of chemically or biologically activecompounds on one side of the object. The package 24 with a bottom 29 hasa recess 26 for receiving the objects 22 and recesses 28 for the holders17 (in the apparatus 10 of FIG. 1).

FIG. 3 shows in enlargement a part of the package 24 and the object 22(with a concentration scale) in the recess 26. The parts of thelongitudal walls of the recess that will come into contact with thelongitudal rims of the object are designated 27.

FIG. 4 shows a cross section of a package 24 with a number of thinobjects 22. In a pick up and lay down head 14 a vacuum has been appliedthrough a channel 15. In the figure is shown how the pick up and laydown head 14 on its way up from the recess 26 of the package 24 bringsthe uppermost of the thin objects 22 while the others remain in thepackage due to the friction and scrape effects towards the interiorwalls of the package 24.

1. A method for separating thin objects, which comprises: providing apackage for thin objects which comprises a package housing being made ofa bendable material selected from the group consisting of a cellularplastic, foamed plastic or foamed rubber with open or closed cells, thepackage housing including a recess for receiving thin objects andcontaining at least two thin stacked objects, said recess having a roughwall rim and an area that is smaller than the exterior dimensions of thethin objects and within which recess said thin objects can be contactedand lifted out of said package housing, said thin objects being made ofplastic and having a chemically or biologically reactive substance on afirst surface thereof; and separating the uppermost thin object from theother thin objects to remove it from the package housing by contactingthe upper surface thereof such that only the uppermost thin objectattains a curved shape when being lifted from the recess because ofsufficient friction provided by said rough wall rim.
 2. The method ofclaim 1, wherein the thin object is formed from a plastic selected fromthe group consisting of polyacrylamide, polyester, polyamide, andpolycarbonate.